# Animation nodes falloff

How to make the center of circle scale down again after scale up? Like a O shape.

There are two ways to do that effect.

1. By controlling the object falloff with Curve Interpolation node,

Blend File 1:

1. Using the Spline Falloff node which gives you more flexibility with the shape (O or something else),

Blend File 2:

One thing I like about Animation Nodes is how flexible it is. Here is a third way to do this kind of effect, using math and an Expression node.

In the GaussianRing loop, we use Vector Length to find the radius of the current position vector. Then we use the Gaussian function to compute the object scale:

a * e ** ((-4 * log(2) * (peakR - r) ** 2) / peakW ** 2)


where:

• r is the current radius
• peakR is the radius of the peak of the bell curve (the center of the ring)
• peakW is the "width" of the bell curve (distance to inflection point)
• a is the amplitude (max scale)